3. Mechanical Properties of the Heart II

Question 1

What phases is the heart beat divided into?

Answer 1

Diastole and Systole

Question 2

Define diastole

Answer 2

Ventricular relaxation during which the ventricles fill with blood

Question 3

Define systole

Answer 3

Ventricular contraction when the blood is pumped into the arteries

Question 4

How many sub-phases are in diastole and systole?

Answer 4

Diastole = 4
Systole = 2

Question 5

What are the 7 events of the cardiac cycle?

Answer 5

1) Atrial Systole
2) Isovolumic contraction
3) Rapid ejection
4) Reduced ejection
5) Isovolumic relaxation
6) Rapid ventricular filling
7) Reduced ventricular filling

Question 6

What type of contraction occurs in diastole?

Answer 6

Atrial contraction is part of diastole, since it is also the filling of ventricles

Question 7

What phase does isovolumetric contraction occur?

Answer 7

Systole - you get contraction but there is no change in volume. The pressure builds until it overcomes the pressure of the afterload

Question 8

What is equation for stroke volume?

Answer 8

SV = EDV - ESV

Question 9

Define ejection fraction?

Answer 9

The proportion of the end diastolic volume that is pumped out of the heart. EJ = SV/EDV

Question 10

What is happening before atrial systole?

Answer 10

The blood flows passively through the open AV valves into the ventricles

Question 11

What does atrial systole achieve?

Answer 11

Tops off the blood volume in the ventricles

Question 12

What is an S4 sound?

Answer 12

During atrial systole an abnormal heart sound can be heard which is caused by valve incompetency.

Question 13

What causes S4?

Answer 13

Pulmonary embolism, congestive heart failure and tricuspid incompetence

Question 14

What is a jugular pulse?

Answer 14

A small pulse in the jugular due to atrial contraction causing some blood to go back up the jugular vein

Question 15

What does the P wave on an ECG stand for?

Answer 15

Atrial depolarisation

Question 16

When does isovolumic contraction occur?

Answer 16

Between when the AV valves closing and the semilunar valves opening. During this period the ventricles are completely sealed off.

Question 17

What does the QRS complex on an ECG stand for?

Answer 17

Ventricular depolarisation

Question 18

What does the first heart sound (S1) signify?

Answer 18

The closing of the AV valves

Question 19

How are the ventricles contracting during isovolumic contraction?

Answer 19

Because they are contracting isometrically the muscle fibres are not changing in length but they are generating force and the pressure increases

Question 20

When does isovolumic contraction end?

Answer 20

When the ventricular pressure exceeds the aortic pressure and blood begins to be ejected

Question 21

What makes the beginning of rapid ejection?

Answer 21

Aortic and pulmonary valves opening

Question 22

What happens to the ventricular volume during rapid ejection?

Answer 22

It decreases

Question 23

What causes the c wave in an atrial pressure graph?

Answer 23

Caused by the right ventricular contraction causing the tricuspid valve to be pushed into the atrium creating a small wave into the jugular vein

Question 24

What does is shown on an ECG during rapid ejection?

Answer 24

No wave

Question 25

What phase marks the end of systole?

Answer 25

Reduced ejection

Question 26

What is seen on an ECG during reduced ejection?

Answer 26

T wave - cardiac cells begin to repolarise

Question 27

What happens during reduced ejection?

Answer 27

Blood leaves the ventricles, ventricular pressure falls, valves begin to close

Question 28

What phase is characterised by the beginning of diastole?

Answer 28

Isovolumic relaxation

Question 29

Is there any change in volume during isovolumic relaxation?

Answer 29

No

Question 30

What valves are open during isovolumic relaxation?

Answer 30

None of them are open

Question 31

What causes the v wave on an atrial pressure graph?

Answer 31

Blood pushing against the tricuspid valve, giving a second jugular pulse

Question 32

What is the dichrotic notch?

Answer 32

A small, sharp increase in aortic pressure due to the rebound pressure against the aortic valve as the distended aortic wall relaxes

Question 33

What does the second heart sound (S2) signify?

Answer 33

When the aortic and pulmonary valves close

Question 34

What occurs during rapid ventricular filling?

Answer 34

AV valves open again resulting in the passive filling of the ventricles

Question 35

What is S3?

Answer 35

A third heart sound that is abnormal; signifies turbulent ventricular filling

Question 36

What is the slow filling of ventricles called?

Answer 36

Reduced ventricular filling = Diastasis

Question 37

What are the differences and similarities between the cardiac cycle of the left and right side of the heart?

Answer 37

Right = lower pressures | Same volume of blood ejected

Question 38

What is the systemic blood pressure value?

Answer 38

120/80 mmHg

Question 39

What is the pulmonary blood pressure value?

Answer 39

25/5 mmHg

Question 40

What is the PAWP?

Answer 40

Pulmonary Artery Wedge Pressure

Question 41

Describe a pressure-volume loop

Answer 41

See diagram

Question 42

Where on the pressure-volume loop is the preload?

Answer 42

Point 1, which is the end diastolic volume

Question 43

Where on the pressure volume loop is the afterload?

Answer 43

Just after point 2, this is when the left ventricle encounters the aortic pressure when the aortic valve begins to open

Question 44

How can the Frank-Starling relationship be applied to hypertension?

Answer 44

High BP = increased afterload = increased pressure to open aortic valve + less shortening so stroke volume decreases

Question 45

Cardiac output =

Answer 45

CO = Stroke volume x Heart rate

Question 46

What is stroke volume affected by?

Answer 46

Preload Afterload Contractility

Question 47

Define contractility

Answer 47

Contractile capability of the heart

Question 48

What is a measure of contractility?

Answer 48

Ejection fraction

Question 49

How can you increase contractility?

Answer 49

Sympathetic stimulation - adrenaline

Question 50

How does an increase in contractility affect the Frank-Starling relationship in terms of a pressure-volume loop?

Answer 50

It shift point 3 to the left, there is an increase in stroke volume as more blood is pumped out

Question 51

What changes occur during exercise?

Answer 51

Contractility is increased due to increased sympathetic activity. End diastolic volume increases due changes in the peripheral circulation

Question 52

Give examples of changes in peripheral circulation

Answer 52

Vasoconstriction and muscle pump. They both increase venous return to the heart

Question 53

What is the EF of a healthy individual?

Answer 53

65%

Question 54

What can the EF of a patient with heart failure drop down to?

Answer 54

35%